In recent years, the use of recirculatory bathtubs of the "spa" or "Jacuzzi" type have become popular for individual homes. Such tubs utilize a circulatory water pump to recirculate water from the tub through a water flow line to air aspirating nozzles located in the tub side walls.
In order to circulate the water and to induce air flow into each nozzle, the fluid flow lines normally are fabricated from plastic pipe sections of various sizes which are solvent-welded into an assembly running from the pump along each tube side wall. To completely fabricate the assembly of water conduit, air conduit, water inlet line, air inlet line, and nozzle connections, as many as 22 solvent welds are required on either side of the tub for a tub equipped with only four nozzles. The cost and the requisite fabrication time, as well as the possibility of leakage at any one of the solvent-welded joints can readily be appreciated.
Various proposals for utilizing combination air and water fittings to reduce the cost and time of fabrication have been made. For example, U.S. Pat. Nos. 3,890,656, 3,946,449, and 4,416,030 have proposed the use of various types of plastic injection molded "T" fittings for insertion into the water and air lines. Separate welds are still required to attach each of the fluid supply lines to each fitting, and a minimum of four welds are still required for each nozzle, plus welds to close any other openings for drilling fluid entry ports. The possibility of multiple leakage points at each of the nozzle locations still exists.
A different proposal is made in U.S. Pat. Nos. 4,240,166 and 2,358,862. Here, a single piece of internally partitioned pipe is wrapped around the tub, and the pipe is drilled at several locations to provide access to the interior water and air passages. A nozzle is then clamped to the pipe and the mixed water and air is conveyed to the tub inlet located remotely from the nozzle, The assembly of the fluid passages is somewhat simplified, but clamping of the nozzles to the composite pipe externally of the pipe can still cause leakage problems. Further, substantial manual labor is still required for bending the pipe around the tub and assembling the nozzles and conduits for the mixed water and air to the tub inlet ports.
Further, the design of the prior art tubs is such that water in the water distribution system will not drain after the pump is shut off. As a result, stagnant water is trapped in the water lines, the pump and the nozzles, so that algae and other growths from organic material in the stagnant water may occur. When the system is next started, this stagnant water enters the tub and contacts the occupant of the tub, possibly causing skin rashes, eye irritation, and the like.
Thus, it will be seen that the prior art recirculating bathtub systems suffer from serious defects. None of the prior art effectively provides a fluid flow system free of leakage at the location of the nozzles. Where the bathtub is installed in an alcove in which only one side of the tub is accessible or in an island, which may be carpeted below the tub level completely around the tub, any leakage causes severe repair problems which are difficult to resolve. Further, none of the prior art discloses any means for effectively draining the water circulatory system to eliminate the health hazards from stagnant water laying in the system for extended periods of time.